Sound translating apparatus



3, 1943- D. o. LANDlS 2,325,688

SOUND TRANSLAT ING APPARATUS Filed May 31, 1940 1 36.3. 9 E7 29 a1 21 2a 3nventor Daniel 0. Landis Patented Aug. 3, 1943 SOUND TRAN SLATING APPARATUS Daniel 0. Landis', Upper Darby, Pa., assignor to Radio Corporation of America, a corporation of Delaware Application May 31, 1940, Serial No. 338,071

3 Claims. (01. 'l79184) This invention relates to sound translating apparatus and more particularly to sound-powered telephones, the present invention being in the nature of an improvement over that disclosed in the co-pending application of Glenn L. Dimmick, Serial Number 338,057, filed May 31, 1940.

Telephones of this type have been used rather advantageously in many communication systems since they are capable of acting either as transmitters or receivers. Systems of this'sort liave been found especially useful on battleships for communication from one part of the ship to another. As heretofore constructed, the diaphragms of the telephone units have been easily subject to damage upon excessive deflection thereof resulting from gun fire, and the principal object of my present invention is to provide an improved telephone unit which will be free from this objectionable feature.

More particularly, it is an object of my present invention to provide an improved soundpowered telephone unit wherein the diaphragm is protected against excessive deflection either in a forward direction as a result of rarefaction of the air in front of the unit, or in a backward direction as a result of the sudden compression of the air in front of the unit.

It is also an object of my present invention to provide an improved sound-powered telephone unit as aforesaid which is simple in construction, highly eflicient in use, and which is economical of manufacture.

According to my invention, I place two similar perforated cover plates parallel to each other in front of the diaphragm and separate their central portions by about .015 inch, the perforations in the plates being in alignment with each other. Between these plates, I provide a flap-valve which is also perforated and the perforations of which are staggered or alternated with respect to the perforations in the aforementioned plates. Preferably, the valve is made in the form of a spider the arms of which are resilient, the valve plate being about'midway between the two cover plates. An application of excessive air pressure from either side of the flap-valve will cause the valve to seat against the openings in the cover plate most remote from the point at-which the excessive pressure is applied, thus preventing the passage of the excessive air pressure to or from the diaphragm and preventing it from being dam aged.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its' organization and method of operation, as well as additional ob jects and advantages thereof, will best be finderstood from the followingdescription of one embodiment thereof, when read in connection with the accompanying drawing, in which Figure 1 is a plan view of a telephone unit embodying my present invention,

Figure 2 is a sectional view thereoftaken on the line 11-11 of Figure l, and

Figure 3 is a detailed plan view of the valve member.

Referring more particularly to the drawing, wherein similar reference numerals designate corresponding parts throughout, I have shown a diaphragm I clamped between a'back plate 3 and a spacing ring 5 by means of a threaded sleeve I'havlng an inwardly extending flange 9. Secured at one end to the diaphragm I is a drive rod II the other end of which is secured to an armature I3 of the cantilever type having one end fixed to a nonmagnetic spacing member l6 between a pair of pole pieces II, an air gap l5 being provided between the pole pieces I1 and a magnet I9 providing the flux for the air gap I5. I Disposed between the ring 5 and the flange 9 is a pair of oppositely disposed, centrally dished,

cover plates 2| the marginal portions 23 of which are disposed in adjacent relation for clamping therebetween the outer 'ends of a plurality of radially extending arms 25 of a flap-valve 21.

The central portions of the plates 2| are provided with a plurality of aligned perforations 29, and the central portion of the flap-valve 21 is providedwith a plurality of perforations 2| which are staggered or alternated with respect to the openings 29.

From the foregoing description, it will be apparent that the flap-valve 21 is a double-acting valve, that is, it can act in opposite directions to cooperate either with the outer plate 2| or the inner plate 2|. Normally, the stiffness of the arms 25 is sufficient to retain the valve member 21 midway between the plates 2 I, as clearly shown in Figure 2, and acoustical waves can pass freely through the openings 29 in the outer plate 2 I, the openings 3|, and then the openings 29 in the inner plate 2| to the diaphragm I to actuate it. When the gun is fired and there is a sudden and excessive rise in air pressure in front of the outer plate 2 I, the valve 21 is forced quickly against the inner plate 2| to close all the openings or ports 29 thereof, whereby the excessive pressure will be prevented from reaching the diaphragm I, thus 65 preventing excessive deflection of the diaphragm I sumcient to damage it. Similarly, if the gun fire results in a sudden rarefactlon of air in front or the outer plate 2|, the valve 21 will be forced against the latter plate to close all the openings 28 therein and therefore the diaphragm I will be prevented from suifering excessive deflection in a forward direction.

From the foregoing description, it will be ap parent to those skilled in the art that I have provided a novel arrangement in sound-poweredtelephones for preventing damage to the diaphragm as a result of sudden and excessive changes in air pressure in the vicinity thereof. Although I have shown and described but a single embodiment of my invention, it will be apparent to those skilled in the art that many other forms thereof, as well as changes in that described, are possible. I therefore desire that my invention shall not be limited except insofar as is made necessary by the prior art and by the spirit of the appended claims.

I claim as my invention:

1. In sound translating apparatus, the combination of an acoustic diaphragm, means vibrativeiy supporting said diaphragm adjacent its periphery for relatively small displacements thereof in response to acoustical energy, a cover structure carried by said means in spaced relation to said diaphragm, said cover structure comprising a pair of dished, oppositely disposed plates having their marginal portions in adjacent relation and their central portions substantially spaced from each other, said central portions each having a plurality of openings therein constituting ports for passage of air waves between the atmosphere and said diaphragm, and a double acting flap valve clamped between the marginal portions of said plates, said valve also having a plurality of openings therein in staggered relation to the openings of said plates, said valve being made of a resilient material and being effective to cooperate with the inner one of said plates to shut off the flow of air therethrough irom the exterior of said apparatus to said diaphragm upon an excessive rise of air pressure in front of the outer one of said plates and being effective to cooperate with the outer one of said plates to shut 03 the flow of air from said diaphragm to the exterior of said apparatus upon an excessive decrease of air pressure in front of said outer plate whereby, in either case, to protect said diaphragm against relatively larg displacements.

2. In sound translating apparatus, the combination of an acoustic diaphragm, means vibra-' tively supporting said diaphragm adjacent its periphery for relatively small displacements thereof in response to acoustical energy, a cover structure carried by said mean inspaced relation to said diaphragm, said cover structure comprising a pair of dished, oppositely disposed plates having their marginal portions in adjacent relation and their central portions substantially spaced from each other, said. central portions each having a plurality of openings therein constituting ports for passage of air waves between the atmosphere and said diaphragm, and a double acting flap valve clamped between the marginal portions of said plates, said valve also having a plurality of openings therein in staggered relation to the openings of said plates, said valve being made of a resilient material and being eflective to cooperate with either one or the other of said plates upon an excessive change in pressure in front of said apparatus to close oil the openings therein and thereby to shut off the flow of air between the exterior of said apparatus and said diaphragm whereby to protect said diaphragm against relatively large displacements.

-3. The invention set forth in claim 2 characterized in that the openings in each of said plates are arranged in aligned relation.

DANIEL O. LANDIS 

